Expressions of interest for a big battery in the Darwin-Katherine network – with a nominal capacity of between 25MW and 45MW, and storage of 30 minutes and 1.5 hours – closed in late January, with 19 companies responding.

Apart from Tesla, there was interest from Infigen Energy, Electranet, MPower, UGL, and Carnegie’s Energy Made Clean, along with New Zealand’s Vector (which is building a 5MW battery in Alice Springs), and international groups Kokam, Mitsui, and Alstom, among others listed here.

The government-owned utility Territory Generation wants the battery to provide contingency frequency control ancillary services (FCAS), reduce the required spinning reserve from its various gas and diesel generators, provide peak shaving, and ultimately allow for more solar PV in the local grid.

Tesla has already built the world’s biggest lithium-ion battery in South Australia, located next to the Hornsdale wind farm, and will build a 20/34MWh battery next to the Bulgana wind project in Victoria that will provide electricity to a new Nectar Farms greenhouse.

Tesla is also said to be a frontrunner for a battery storage project near Cairns, with Hornsdale owner Neoen, that could be bigger than Hornsdale – but Neon’s Franck Woitiez says those plans are in the very early stages, and will depend on the rollout of Queensland’s upcoming renewable energy auction.

Territory Generation, meanwhile, says it needs a battery because it is running some 40–50MW of “spinning reserve” in the case of an outage of one of its fleet of gas generators, and fears this need may increase as more solar is added to the grid over the medium term.

The grid in Darwin and Katherine has demand ranging from just below 100MW to nearly 300MW, with an average of around 195MW.

So far, it has little in the way of solar PV, with only 10% of households with rooftop solar and just eight larger scale solar installations (more than 100kW) totalling 8.2MW.

Territory Generation also expects household solar penetration to nearly triple to 29% by 2025, and appears to have a conservative view on the grid’s ability to handle it.

“The fluctuations and step changes in generation due to cloud cover has a negligible effect on power system stability at this stage,” it says in its tender documents.

“However, with penetration levels increasing to more than 10 percent of the total load issues with voltage and frequency regulation start to arise.

“It is, therefore, a requirement that an energy storage system with sufficient capacity can supply during these periods of large solar PV capacity loss where machine ramp up/down rates are not fast enough to respond.”

However, it also notes that the battery will not be required for shifting solar output, or smoothing solar output, in the short term.

The utility wants the battery storage array to reduce the need for spinning reserve by around half, and is open to various configurations — between 25MW and 45MW of nominal capacity — and at least 30 minutes of storage.

Proposals are due by August/September this year, with the battery due to be in service by the end of the 2018/2019 financial year.

About the Author

Giles Parkinson is the founding editor of RenewEconomy.com.au, an Australian-based website that provides news and analysis on cleantech, carbon, and climate issues. Giles is based in Sydney and is watching the (slow, but quickening) transformation of Australia's energy grid with great interest.

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